Process of creaseproofing linen fabric by applying resin, mercerizing and reapplyingresin and product produced thereby



United States Patent O PROCESS OF CREASEPROOFING LINEN FABRIC BYAPPLYING RESIN, MERCERIZING AND RE- APPLYING RESIN AND PRODUCT PRODUCEDTI-IEREBY Frederick Charles Wood, Manchester, England, assignor toTootal Broadhurst Lee Company Limited, Manchester, England, a Britishcompany 7 No Drawing. Filed Apr. 19, 1957, Ser. No. 653,760

Claims priority, application Great Britain Apr. 19, 1956 11 Claims. (Cl.8-115.6)

This invention relates to improvements in the treatment with syntheticresins of linen textile fabrics manufactured wholly or partly from flax.

In the treatment of linen textile fabrics to improve their resistanceto, and recovery from, creasing by the formation of a synthetic resininside and substantially not outside the fibres of the fabric, it hashitherto been customary to treat the fabric with resin-formingcondensation products by means of a single impregnation and after resinformation to subject the fabric to a swelling, or swelling andshrinking, treatment. Thus it has been customary to treat linen fabrics,which have been treated with resinjwith a swelling agent in the mannerdescribed in our U.S. Patent No. 2,158,494. The quantity of resin formedin the linen fabric when treated according to the example of U.S. PatentNo. 2,158,494 is about 15%. It is necessary to iron fabrics treated inthis manner after normal use and washing.

By the process of the present invention, however, there is produced alinen textile fabric having good creaseresisting properties, andmoreover having such properties that a garment made of such fabric andwhich has been worn, washed and dried, needs only the minimum ofpressing or ironing before being worn again. Linen fabrics treatedaccording to the present invention have such smooth drying properties toa greater degree than linen fabric treated by hitherto known processes.

The condensation of formaldehyde with urea to produce a resin-formingcondensation product is customarily carried out in the presence of aquantity of a solution in water of ammonia having a specific gravity of0.88, equivalent to 8.8% by weightcalculated on the weight of urea, ascondensing agent. When this quantity of ammonia is used in preparing theresin-forming condensation product from formaldehyle and urea in themolecular proportion of 1.6:1, one tenth of the quantity of formaldehydecombines with the ammonia and is prevented from combining with the urea,and the equivalent proportions will be different if larger or smallerquantities of ammonia or no condensing agent, or a condensing agentother than ammonia, is used. Thus a molecular proportion of formaldehydeto urea of 1:6;1 in the presence of a quantity of a solution in water ofammonia havinga specific gravity of 0.88, equivalent to 8.8% by weightcalculated on the weight of urea is equivalent to a molecular proportionof 1.6 9/10:l, i.e. 1.44:1 where no condensing agent, or a condensingagent other than ammonia, is used. Where higher molecular proportions offormaldehyde to urea than 1.6;1 are used then the proportion offormaldehyde which is prevented from combining with the urea comparedwith the total quantity of formaldehyde present is less than one tenthin simple proportion. Similarly where larger or smaller quantities ofammonia than the customary quantity stated above are used, the quantityof formaldehyde which is prevented from combining with the urea variesin simple proportion. In the present invention where condensing agentswhich do not combine with the formaldehyde are used or greater or lessquantities of ammonia are used, suitable adjustments to the molecularproportions must be made.

According to the present invention, a process for the production of alinen textile fabric having thermosetting synthetic resin within andsubstantially not beween the fibers is provided in which the fabric is,in a first stage, impregnated with a low-viscosity resin-formingcondensa tion product, which penetrates Within the fibers of the fabric,formed from urea and formaldehyde in the molecular proportion offormaldehyde to urea between the limits of 1.4:1 and 2.521 inclusive andcontaining an acidic or potentially acidic catalyst, the fabric thenbeing heated to form such resin and thereafter being subjected to aswelling, or swelling and shrinking, process as set forth in our U.S.Patent :No. 2,158,494, and in which, in a second stage, the fabric isfurther impregnated with a low-viscosity resin-forming condensationproduct, which penetrates within the fibers of the fabric, formed fromurea and formaldehyde in the molecular proportion of formaldehyde tourea between the limits 1.4:1 and 2.521 inclusive and containing anacidic or potentially acidic catalyst, the fabric again being heated toform such resin without thereafter being subjected to a swelling, orswelling and shrinking, process, the amount of resin formed in thefabric as a result of the first stage impregnation and remaining in thefabric after the swelling, or swelling and shrinking, process beingbetween the limits of 1% and 13% inclusive, the amount of resin formedin the fabric as a result of the second stage impregnation being betweenthe limits 1% to 9% inclusive, and the total amount of resin in thefabric being between the limits of 4% and 18% inclusive, the percentageresin contents being calculated on the weight of the dry fabric beforetreatment and the molecular proportions of formaldehyde to urea beingcalculated on the basis that a quantity of a solution of ammonia inwater having a specific gravity of 0.88, equivalent to 8.8% by weightcalculated on the weight of urea is to be added as condensing agent, orthe equivalent molecular proportion Where a larger or smaller quantityof ammonia or no condensing agent or a condensing agent other thanammonia is to be used.

We prefer in treating line fabrics according to this invention to usemolecular proportions of formaldehyde to urea in both stages ofimpregnation between the limits of 1.421 and 2.0:1 inclusive calculatedon the basis that a quantity of a solution of ammonia in water having aSpecific gravity of 0,88, equivalent to 8.8% by weight calculated on theweight of urea is to be added as condensing agent, or the equivalentmolecular proportion where a larger or smaller quantity of ammonia or nocondensing agent or a condensing agent other than ammonia is to be used.We prefer to treat such fabrics so that the quantity of resin formed inthe fabric as a result of the first stage impregnation and remaining inthe fabric after the swelling, or swelling and shrinking, treatment isbetween the limits 3 and 8% inclusive, and so that the quantity of resinformed in the fabric as a result of the second stage impregnation isbetween. the limits 3 and 6% inclusive and so that the total quantity ofresin in the fabric is between the limits of 6 and 14% inclusive.

All percentages of resin contents given hereinafter are calculated onthe weight of the dry fabric before treatment with resih-formingcondensation product.

In carrying out the present invention it is preferred to use such anamount of resin-forming condensation product in the first stage that theamount of resin remaining in the fabric after the swelling, or swellingand shrinking, process is smaller than is normally used to producecrease resisting properties. The formation in the fabric in the secondstage of a suitable amount of synthetic resin to bring about theproduction of good dry crease-resisting properties results in theproduction, in addition, of good smooth drying properties. Indeed, it ispossible by treating the ing, process. has in addition good smoothdrying properties.

linen fabric with resin-forming condensation product in two stages, ofwhich only the first stage includes a subsequent swelling, or swellingand shrinking, process, to obtain better dry crease-resisting propertiesthan are :obtained by the same quantity of resin insolubilised in asingle stage which includes such subsequent swelling, or

second stage to give a total resin content of 12%, a

better dry crease-resisting property is developed which is moreoverbetter than that of a fabric treated so as to contain 10-12% of resinusing formaldehyde and urea in the molecular proportion of 1.6:1 after asingle impregnation followed by a swelling, or swelling and shrink-Moreover the fabric treated in two stages The swelling, or swelling andshrinking, process is carried out with any of the swelling agents,including caustic soda of mercerizing strength, and in the mannerdescribed, in our prior specification No. 2,158,494. 'the preferredembodiment of this invention where the amount of resin formed in thefabric during the first stage of the process of this invention issmaller than the amount normally used in a one stage process, theswelling, or swelling and shrinking, of the fabric takes place morerapidly than normally. During this process some of the synthetic resinwhich has been insolubilised by heating is removed, and this must betaken into account in adjusting the treatment so that the requiredquantity of resin remains in the fabric after the first stage of thetreatment and in the final fabric. The quantity of resin should beadjusted so that the final fabric possesses simultaneously goodcrease-resisting and good smooth drying properties, and good physicalproperties of tensile strength and resistance to wear. Furthermore thehigher the molecular proportion of formaldehyde to urea used in formingthe resin in both stages of impregnation, the smaller the total 'amountof resin which it is preferred to form on the fabric because theresistance to wear of the finished fabric may be seriously affected.Thus when using molecular proportions of formaldehyde to urea greaterthan 2:1 in both stages of impregnation we prefer that the total amountof resin formed in the fabric should not exceed 12% or better should notexceed 8%.

Conversely the lower the molecular proportion of formaldehyde to ureaused in forming the resin in both stages of impregnation, the greaterthe total amount of ,of ammonia or no condensing agent or a condensingagent other than ammonia is to be used, we prefer that the total amountof resin formed on the fabric should be at least 7%, or better at least9%.

We prefer, according to this invention, to treat linen fabrics whichhave not been mercerized before resin treatment. It has been found thatif treatment of the fabric, including mercerization, prior to the firststage resin treatment is kept to a minimum, better all round physicalproperties, for example crease-resisting properties and resistance towear are obtained.

Linen fabrics which have not been mercerized and which have received thefirst resin treatment and then 4 been subjected to a swelling, orswelling and shrinking, process, may then be dyed. In this way a bettercolour yield is frequently obtained in comparison with the same fabricwhich has been dyed before resin treatment, thereby reducing dyestuffcosts, and since the fabrics are not subsequently subjected to a severecaustic alkali treatment the range of dyestufis which may be used isincreased.

The treatment of linen fabrics according to this invention may includetreatment with a lubricating agent for example as described in ourBritish application No. 31150/55, filed November 1, 1955. Suitablelubricating agents are a methylol derivative of a condensation productof a higher fatty acid chloride with a polyethylene polyamine sold underthe trade name Sapamine WP, or a dimethylol stearyl melamine sold underthe trade name Phobotex PT.

The resin may be formed in either or both stages of the treatment inatmospheres containing more than 50% of superheated steam, for exampleas described in our prior U.S. specification No. 529,774, filed August22, 1955, now U.S. Patent 2,859,136.

The catalyst present in the impregnating mixtures may be a weak acid,such as tartaric acid, or a potential acid, such as ammonium dihydrogenphosphate, which liberates acid on heating in the presence of theimpregnating mixture. Alternatively we may use the acid salt of apolybasic acid having a dissociation constant in water of not less than10 with a metal of which a less acid salt with the same polybasic acidis precipitated before said acid salt on concentration and/or on heatingthe solution, for example sodium dihydrogen phosphate and magnesiumsulphate, as described in our co-pending U.S. application No. 581,508,filed April 30, 1956. When steam is used to form the resin such catalystis preferably one which does not develop sufiicient acidity during thelow temperature drying to form more than a very small proportion of thetotal resin formed on the fabric to ensure that as much as possible ofthe resin is formed in the presence of superheated steam.

The low viscosity resin forming condensation products formed from ureaand formaldehyde which are used in the present invention, may bealkylated to form alkylated methylol ureas and then used to impregnatelinen textile fabrics according to the present invention.

By linen textile fabric we mean fabric containing at least 25% by weightof flax. The present invention therefore includes the treatment ofmixture fabrics containing at least 25% by weight of flax and alsocontaining other cellulosic fibre such as cotton or regeneratedcellulose or non-cellulosic fibres such as nylon.

. The invention will be more clearly understood by reference to thefollowing examples which are purely illustrative.

EXAMPLE 1 2 gallons of aqueous formaldehyde solution containing 40grammes of formaldehyde per ccs. of solution, 10 lb. of urea (molecularproportion of formaldehyde to urea 1.621) and 40S ccs. of ammonia(specific gravity 0.88) were allowed to stand at room temperature untilthe mixture reached equilibrium in density and viscosity. This mixturewas diluted until the density was 19 Tw. (approximately 5% gallons).

To 5% gallons of this mixture was added 14 oz. of ammonium dihydrogenphosphate dissolved in a little water, 4 oz. of a mixture of sodiumcetyl and oleyl sulphates mixed with water and the mixture was furtherdiluted with Water to about 10 gallons. 'I he density of this mixture(Mixture A) was 10 Tw.

A portion of Mixture A was further diluted with water until its densitywas 7 Tw., Mixture B.

First stage impregnation An absorbent fabric made of 100% flax andweighseesaw tag 200 g'ms. per square metre and having in the 160m state25 combed tow warp threads per i'nch and 32 combed tow weft threads perinch, of 30 and 25 lea respectively, previously well scoured andbleached was impregnated with Mixture A and passed between the bowls ofa triangle adjusted so as to leave about 65% or liquor on the fabric,dried on a stenter and then heated at 300 F. for three minutes. Thefabric was then passed through an aqueous solution containing as wettingagent of an alkali salt of a sulphonated fatty alcohol and /4% of sodaash at 80 C. The fabric was then squeezed and whilst still wet run intoa bath of 65 Tw. caustic soda. It was then lightly squeeied so as toleave caustic soda on the fabric and was allowed to stand withouttension either in warp or Wait far minutes during which time it wasallowed to shrink in both direc tions. The fabric was then washed withwater over a r'nercerizing stenter until neutral and dried on stemheated cylinders. At this stage the fabric contained 4.7% of resin.

Second stage impregnation The treated fabric was then impregnated withMixture B, dried and heated in the same way as iii the first stageimpregnation. It was then washed at 80 C. for 30 seconds in /2% sodaash, washed in water and mangled and passed through a bath containing 1%of a mixture of 3 parts of stearin to l of bora'x, and dried on steamheated cylinders. It was then damped with water and cold and calenderedand finished on a controlled compressive shrinkage machine.

By the second stage impregnationthe fabric was treated with a further4.3% of resin and the total resin content of the finished fabric was9.0%.

The finished fabric showed excellent dry crease-resistance and dressesmade of the fabric could be worn, washed, squeezed free of excess waterand when dried by hanging on a clothes hanger they could be worn withoutbeing ironed. The fabric had these properties to a greater degree than asimilar fabric treated so as to contain 9.0% of resin by a singleimpregnation followed by a swelling and shrinkage treatment.

6 nation was used for an samples. The variariensuse are shown in thetable given below.-

Each sample was then tested to obtain its Smooth Drying Index (S.D.I.),Ring Wear (R.WJ figures.

The S.D.I. figures were obtained by use of the apparatus described inour co pending U.S. applicationNo. 628,902, filed December 17, 1956, newPatent 2,909,921 and consisting of (1) a crease maker, 2) a dryingcabinet, and (3) a crease gauge.

Specimen strips of the fabric under test are cut in both warp and weftdirections. These are weadom, squeezed through a small domestic mangle,and inserted in the crease maker in order to forth a sharp doublecrease. The specimen is next dried for half an hohr and during dryingthe crease inserted iii the wet fabric diminishes. The S.D. I. figni'reis obtained from the extent of this recovery and it indicates 'theability of the fabric to recover from creases formed during hormaldomestic washing.

The extent of this recovery is measured by placing the dried sample inthe cabinet of the crease gauge and the angle of the residual crease ismeasured from observation of the shadow cast by the crease whenilluminated by a directional light source. The smaller the figureobtained in this test the better is the fabrics property of needinglittle or no ironing after washing.

The R.W. figures were obtained by use of the Ring Wear Machine describediii the Textile Recorder Year Book 1942-3 page H36. In this machine astandard wool fabric is placed over the face of one disc: and the testfabric is placed over the face of another disc of similar size. The twodiscs are placed face to face so that the wool fabric and the testfabric are in friction contact, one disc being offset fromthe other, so.that the circumference of each disc passes through the approximatecentre of theother. To test the abrasion resistance of the test fabricboth discs are set to revolve until the test fabric breaks down underfriction with the wool fabric. The number of revolutions required toreach this point is taken as a measure of the resistance to wear.

All the samples treated and tested showed good resistance to creasing inthe dry state.

Ratio of formaldehyde Strength of Physical Properties to urea Resin,Percent impregnating oi finished fabric mixture, 'Iw.

2nd 1st 2nd 1st 2nd R.W.(No. 1st Stage Stage Stage Stage Total StageStage S.D.I. fitiievoi u one 13 4 17 28 6% 11 800 8 6 14 17 1O 11 9301.4 1. 4 7 4 11 15 6% 12 1,400 5 4 9 10% 6% 12% 1, 470 2 6 8 4 10 12% 1,200 11 4 15 23 6% 10% 900 7 4 11 15 6% 13 950 1.4 1. 8 7 3 10 15 5 14 1,200 5 3 8 10% 6 12% 1, 100 2 4 6 4 6% 13% 950 8 2 10 17 3 11 1,050 1.42. 5 7 2 9 15 3 11 1,200 2 3 5 4 5 12 1, 000 Ratios between 8 3 11 15 512% 850 2.0 and 2.5 m 1. 4 4 3 7 7 5 13 1, 200 cluswe' t g is 1% 1g i 141 g gg gfg g 1.8 4 2 s 7 a 12 1, 050 i t s a 12 22s g g g gfg g 2. s 4 1s 1 1% 12 1,100 i 3 t 1% S 13 1638 Ratios between 2.0 4 2 B 7 3 12 1,200 2.0 and 2.5. 1 3 4 2 5 M 1, 000

EXAMPLE 2 Different samples of a fabric as in Example 1 were treated asdescribed in Example 1, but suitable adjustments were made in thequantities of urea and formaldehyde used and in the extent of dilutionof the partially condensed mixture, to form on the samples differentquantities of resin. Mangle adjustment so as to leave about of liquor onthe fabric after impreg- I claim:

1. A process for improving the crease resisting and smooth dryingproperties of a linen textile fabric contain ing at least 25% by weightof flax comprising the steps of impregnating said fabric with a lowviscosity resin forming solution comprising formaldehyde, urea and acatalyst for the reaction of said formaldehyde and said urea, themolecular proportion of said formaldehyde to '7 said urea being from1.4:1 to 2.5 :1, applying heat to the impregnated fabric to insolubilizethe ureaformaldehyde reaction product-within-the fibres of the fabric,

mercerizing said fabric with a mercerizing agent under conditions whichpermitthe fabric to shrink, said fabric having a urea-formaldehyde resincontent of from 1 to 13% inclusive based on the weight of the dry fabricprior to treatment, further impregnating said treated fabric with saidlow viscosity resin-forming solution, heating said impregnated fabric toinsolubilize additional ureaformaldehyde resin within the fibres of saidfabric, said additional resin being present in an amount of from 1 to 9%based upon the'weight of the dry fabric, the total weight of the resinon the fabric being within the range of 4 to 18% inclusive, said fabricbeing held in a flat .position after each of said impregnating stepswhile said resin is being insolubilized thereon.

2. Process as claimed in claim 1 in which the quantity of resin formedin the fabric as a result of the first step impregnation and remainingin the fabric after being mercerized by the mercerizing agent is betweenthe limits of 3% and 8% inclusive.

3. Process as claimed in claim 1 in which the quantity of resin formedin the fabric as a result of the second step impregnation is between thelimits of 3% and 6% inelusive.

4. Process as claimed in claim 1 in which the total quantity of resin inthe fabric is between the limits of 6% and 14% inclusive.

5. Process as claimed in claim 1 in which the linen fabric has beenscoured and bleached but not mercerized before the first impregnationstep.

6. Process as claimed in claim 1 in which the heating to form the resinafter one of said impregnation steps is effected in an atmospherecontaining more than 50% of superheated steam.

7. Process as claimed in claim 1 in which the heating to form the resinafter both impregnation steps is effected in an atmosphere containingmore than 50% of superheated steam.

.; 8. The process as defined in claim 1 wherein said molecularproportions of formaldehyde to urea are beween, the. l mi s .Qff...-4.=.. and. :1 clus ve... H

9. The process as defined in claim 1 wherein said fabric is made of 100%flax.

10. A process for improving the crease resisting and smooth dryingproperties of a linen textile fabric containing at least 25% by weightof flax comprisingthe steps of impregnating said fabric with a lowviscosity resin-forming aqueous solution comprising formaldehyde, ureaand a catalyst for the reaction of said formaldehyde and said urea, themolecular proportion of said formaldehyde to said urea being from 1.4:1to 20:1,

applying heat to the impregnated fabric to insolubilize theurea-formaldehyde reactionproduct within the fibres of the fabric,mercerizing said fabric with a mercerizing agent under conditions whichpermit the fabric to shrink,

15 said fabric having a ur ea-formaldehyde resin content of from 3 to 8%inclusive based on the weight of the dry fabric prior to treatment,further impregnating said treated fabric with said low viscosityresin-forming solution, heating said impregnated fabric to insolubilizeadditional urea-formaldehyde resin, said additional resin being withinthe range of 3 to 6% based upon the weight of the dry fabric, the totalweight of the resin on the fabric being within the range of 6 to 14%inclusive, said fabric being held in a flat position after each of saidimpregnating steps while said resin is being insolubilized thereon.

11. The crease-resistant and smooth-drying linen tex tile fabricproduced by the process defined inclaim 1.

. OTHER REFERENCES 7 Marsh, John T.: An Introduction to TextileFinishing,

1 943, pages 390, 402.

1. A PROCESS FOR IMPROVING THE CREASE RESISTING AND SMOOTH DRYINGPROPERTIES OF A LINEN TEXTILE FABRIC CONTAINING AT LEAST 25% BY WEIGHTOF FLAX COMPRISING THE STEPS OF IMPREGNATING SAID FABRIC WITH A LOWVISCOSITY RESINFORMING SOLUTION COMPRISING FORMALDEHYDE, UREA AND ACATALYST FOR THE REACTION OF SAID FORMALDEHYDE AND SAID UREA, THEMOLECULAR PROPORTION OF SAID FORMALDEHYDE TO SAID UREA BEING FROM 1.4:1TO 2.5:1, APPLYING HEAT TO THE IMPREGNATED FABRIC TO INSOLUBILIZE THEUREA-FORMALDEHYDE REACTION PRODUCT WITHIN THE FIBRES OF THE FABRIC,MERCERIZING SAID FABRIC WITH A MERCERIZING AGENT UNDER CONDITIONS WHICHPERMIT THE FABRIC TO SHRINK, SAID FABRIC HAVING A UREA-FORMALDEHYDERESIN CONTENT OF FROM 1 TO 13% INCLUSIVE BASED ON THE WEIGHT OF THE DRYFABRIC PRIOR TO TREATMENT, FURTHER IMPREGNATING SAID TREATED FABRIC WITHSAID LOW VISCOSITY RESIN-FORMING SOLUTION, HEATING SAID IMPREGNATEDFABRIC TO INSOLUBILIZE ADDITIONAL UREAFORMALDEHYDE RESIN WITHIN THEFIBRES OF SAID FABRIC, SAID ADDITIONAL RESIN BEING PRESENT IN AN AMOUNTOF FROM 1 TO 9% BASED UPON THE WEIGHT OF THE DRY FABRIC, THE TOTALWEIGHT OF THE RESIN ON THE FABRIC BEING WITHIN THE RANGE OF 4 TO 18%INCLUSIVE, SAID FABRIC BEING HELD IN A FLAT POSITION AFTER EACH OF SAIDIMPREGNATING STEPS WHILE SAID RESIN IS BEING INSOLUBILIZED THEREON.